feat: allow user to pass sync and async function returning boolean fl…

…ag (#162)

README.md

@@ -146,6 +146,22 @@ onlyOn(S === 'foo', () => {
 })
 ```
 
+Also you can pass sync and async function returning boolean flag.
+
+```js
+// run this test if function returns true
+const fnReturningTrue = () => true
+
+cy.onlyOn(fnReturningTrue())
+```
+
+```js
+// run this test if async function returns true
+const fnReturningPromiseTrue = () => new Promise((resolve) => resolve(true))
+
+cy.onlyOn(fnReturningPromiseTrue())
+```
+
 You can even run other Cypress commands before deciding to skip or continue
 
 ```js

cypress/integration/function-spec.js

@@ -0,0 +1,37 @@
+/// <reference types="cypress" />
+import { onlyOn, skipOn } from '../..'
+
+const functionReturningTrue = () => true
+const asyncFunctionReturningTrue = () => new Promise((resolve) => resolve(true))
+
+it('runs on true', () => {
+  onlyOn(functionReturningTrue())
+})
+
+it('skips on true', () => {
+  skipOn(functionReturningTrue())
+})
+
+onlyOn(functionReturningTrue(), () => {
+  it('runs it as callback', () => {})
+})
+
+skipOn(functionReturningTrue(), () => {
+  it('skips this completely', () => {})
+})
+
+it('runs on true', () => {
+  onlyOn(asyncFunctionReturningTrue())
+})
+
+it('skips on true', () => {
+  skipOn(asyncFunctionReturningTrue())
+})
+
+onlyOn(asyncFunctionReturningTrue(), () => {
+  it('runs it as callback', () => {})
+})
+
+skipOn(asyncFunctionReturningTrue(), () => {
+  it('skips this completely', () => {})
+})

index.js

@@ -80,6 +80,8 @@ const isBrowser = (name) => ['electron', 'chrome', 'firefox'].includes(name)
 const isHeadedName = (name) => ['headed', 'headless'].includes(name)
 const isEnvironmentSet = () =>
   typeof Cypress.env('ENVIRONMENT') === 'string' && Cypress.env('ENVIRONMENT')
+const isAsyncFn = (name) =>
+  Object.prototype.toString.call(name) === '[object AsyncFunction]'
 
 const headedMatches = (name) => {
   if (name === 'headed') {
@@ -129,12 +131,22 @@ const skipOnBool = (flag, cb) => {
 
 /**
  * Skips the current test based on the browser, platform or url.
+ * @param {string|boolean|Function} name - condition, could be platform, browser name, url or true|false.
+ * @param {() => void} cb - Optional, run the given callback if the condition passes
  */
 const skipOn = (name, cb) => {
   if (_.isBoolean(name)) {
     return skipOnBool(name, cb)
   }
 
+  if (isAsyncFn(name)) {
+    return name().then((result) => onlyOnBool(result, cb))
+  }
+
+  if (_.isFunction(name)) {
+    return onlyOnBool(name(), cb)
+  }
+
   if (!_.isString(name) || '') {
     throw new Error(
       'Invalid syntax: cy.skipOn(<name>), for example cy.skipOn("linux")'
@@ -226,7 +238,7 @@ const onlyOnBool = (flag, cb) => {
 
 /**
  * Runs the current test only in the specified browser, platform or against url.
- * @param {string|boolean} name - condition, could be platform, browser name, url or true|false.
+ * @param {string|boolean|Function} name - condition, could be platform, browser name, url or true|false.
  * @param {() => void} cb - Optional, run the given callback if the condition passes
  */
 const onlyOn = (name, cb) => {
@@ -240,6 +252,14 @@ const onlyOn = (name, cb) => {
     )
   }
 
+  if (isAsyncFn(name)) {
+    return name().then((result) => onlyOnBool(result, cb))
+  }
+
+  if (_.isFunction(name)) {
+    return onlyOnBool(name(), cb)
+  }
+
   if (cb) {
     if (isOn(name)) {
       return cb()